Carbon dots as versatile photosensitizers for solar-driven catalysis with redox enzymes

Hutton, Georgina A. M., Reuillard, Bertrand, Martindale, Benjamin C. M., Caputo, Christine A., Lockwood, Colin W. J., Butt, Julea N. ORCID: https://orcid.org/0000-0002-9624-5226 and Reisner, Erwin (2016) Carbon dots as versatile photosensitizers for solar-driven catalysis with redox enzymes. Journal of the American Chemical Society, 138 (51). 16722–16730. ISSN 0002-7863

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Abstract

Light-driven enzymatic catalysis is enabled by the productive coupling of an enzyme to a photosensitizer. Photosensitizers used in such hybrid systems are typically costly, toxic and/or fragile, with limited chemical versatility. Carbon dots (CDs) are low-cost nano-sized light-harvesters that are attractive photosensitizers for biological systems as they are water-soluble, photostable, non-toxic and their surface chemistry can be easily modified. We demonstrate here that CDs act as excellent photosensitizers in two semi-biological photosynthetic systems utilizing either a fumarate reductase (FccA) for the solar-driven hydrogenation of fumarate to succinate, or a hydrogenase (H2ase) for reduction of protons to H2. The tunable surface chemistry of the CDs was exploited to synthesize positively charged ammonium-terminated CDs (CD-NHMe2+), which were capable of transferring photo-excited electrons directly to the negatively charged enzymes with high efficiency over 24 h. Enzyme-based turnover numbers of 6000 mol succinate (mol FccA)−1 and 43 000 mol H2 (mol H2ase)−1 were reached after 24 h. Negatively charged carboxylate-terminated CDs (CD-CO2–) displayed little or no activity and the electrostatic interactions at the CD–enzyme interface were determined to be essential to the high photocatalytic activity observed with CD-NHMe2+. The modular surface chemistry of CDs together with their photo-stability and aqueous solubility make CDs versatile photosensitizers for redox enzymes with tremendous scope for their utilization in photobiocatalysis.

Item Type: Article
Additional Information: ACS AuthorChoice - This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.
Faculty \ School: Faculty of Science > School of Chemistry
Faculty of Science > School of Biological Sciences
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Depositing User: Pure Connector
Date Deposited: 01 Dec 2016 00:03
Last Modified: 21 Oct 2022 08:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/61553
DOI: 10.1021/jacs.6b10146

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